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Leonardo, Old Man with Water Studies, c. 1513

For him it was full of paradox:

"Water is sometimes sharp and sometimes strong, sometimes acid and sometimes bitter, sometimes sweet and sometimes thick or thin, sometimes it is seen bringing hurt or pestilence, sometime health-giving, sometimes poisonous. It suffers change into as many natures as are the different places through which it passes. And as the mirror changes with the colour of its subject, so it alters with the nature of the place, becoming noisome, laxative, astringent, sulfurous, salty, incarnadined, mournful, raging, angry, red, yellow, green, black, blue, greasy, fat or slim. Sometimes it starts a conflagration, sometimes it extinguishes one; is warm and is cold, carries away or sets down, hollows out or builds up, tears or establishes, fills or empties, raises itself or burrows down, speeds or is still; is the cause at times of life or death, or increase or privation, nourishes at times and at others does the contrary; at times has a tang, at times is without savor, sometimes submerging the valleys with great floods. In time and with water, everything changes"

Leonardo described water as "the vehicle of nature" ("vetturale di natura"), believing water to be to the world what blood is to our bodies.

As Leonardo understood it, water circulated according to fixed rules. It fell as rain or snow, springs from the ground, and runs in streams and rivers to the vast reservoir of the seas.

Water is indispensable to humans, animals and plants, yet it can also be the instrument of their destruction. Its power is irresistible.

Leonardo had witnessed great storms, and conducted numerous studies of the motion of water.

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Leonardo, Study of water passing obstacles, c. 1508-9

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Leonardo, Study of water falling into still water, c. 1508-9

He examined the motion of waves and currents, and was the first to postulate the principle of erosion: "Water gnaws at mountains and fills valleys. If it could, it would reduce the earth to a perfect sphere" (Codex Atlanticus, 185v).

Leonardo studied water also with the view to learning how to control it. Throughout his life, Leonardo was obsessed with a fear of a great watery cataclysm. In his drawings and in his writings he describes terrible floods and inundations and great storms.

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Leonardo, Storm over an Alpine Valley
(Windsor, Royal Library, c. 1499)

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Leonardo, End of the World
(Windsor, Royal Library, 1515)

His drawings indicate a special fear of swirling waters. There is nothing more terrifying, he felt, than a swollen river breaking its banks and sweeping people, animals, houses, trees, and even the land itself down into the sea. Leonardo had witnessed such disasters when the Arno river burst its banks on 12 January 1466, and again in 1478.

Perhaps as a result of these events, and as a way of dealing with his fears, Leonardo devoted a lot energy to developing ways or devices to control and move water around water.

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Leonardo, Machine for raising water
(Codex Atlanticus, f. 26v)

He also designed locks and canal systmes, and invented machines for excavating canals.

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Leonardo, Machine for excavating canals
(Codex Atlanticus, f. 4v)

One large scale but never realized plan was for a navigable canal linking Florence to the sea. The scheme included cutting a series of giant steps with locks to enable ships to sail up into the hills. The water would be raised from one level to the next by a huge siphon. In Milan, he worked on a system of locks and paddle wheels for washing the streets. He also had plans for draining the unhealthy marshes of the Val di Chiana.